1. Field of the Invention
The present invention relates to technology for remotely connecting to a network; and more particularly to managing traffic flow across communication links between a remote node and a local network.
2. Description of Related Art
Local area network (LAN) technology has been evolving to provide interconnection among LANs to establish corporate-wide networks. For businesses with remote offices, there is a need to interconnect remote offices to the corporate network, with technology referred to as remote networking. Remote networking extends the logical boundaries of the corporate LAN to give remote offices, telecommuters, and mobile users access to critical corporate resources.
One important user of remote networking is the single user working remotely from an office or on the road, who has a need to exchange data with the corporate network via dialup connections or other communications media.
For these smaller users of network resources, the cost of dedicated network connections is usually prohibitive. Thus, they rely on dialup connectivity, using high speed modems and analog links, ISDN terminal adapters and basic rate interface (BRI) services, or other DSU/CSU devices and Switched 56 lines. A mobile user of the corporate network, such as a business traveler may rely on analog dialup access as their only connection alternative to the corporate.
There are many broadcast and multicast packets which appear on LANs. Most of these packets are useless to a remote node, especially when they relate to a protocol not in use by the remote node. When a user is directly connected to a LAN, such as Ethernet or TokenRing, the performance impact on the user of these broadcast and multicast packets is minimal because of the substantial bandwidth of the LAN. However, for remote nodes connected to a LAN via a switched communication link, such packets have a large impact on the performance of the remote node because they consume a substantial part of the bandwidth of the switched network connection.
One prior art system for providing remote access is known as the AccessBuilder Remote Access Server, manufactured by 3Com Corporation of Santa Clara, Calif. The remote access server manages multiple simultaneous protocols in the corporate LAN and the forwarding of data packets between the switched connection to the remote node, and the corporate LAN. This device includes a multiprotocol engine and a series of node emulators. The multiprotocol engine handles all addressing, routing information, and routing tables for the remote clients dialing into a LAN environment. From the perspective of both the remote node and the corporate LAN, the multiprotocol engine appears local to the corporate LAN segment.
Node emulators are logical nodes that serve as proxies for the remote nodes. To the corporate network and the network manager, the node emulator appears as an actual node residing on the corporate LAN. In this way, the node emulator provides a point of stability that masks the otherwise transitory character of the dialup remote access.
When a user dials into the node emulator, it is assigned an address. All traffic from the remote client issues from this address, and all traffic sent to the remote client filters through this address.
Because clients dial in from many different types of environments, each running different protocols, each node emulator must adapt its functionality dynamically. On a client-by-client basis, each node emulator conforms to the relevant protocol suite of the remote node it currently represents.
One type of traffic which must be managed by the remote access server is broadcast and multicast packets. The prior art AccessBuilder product includes a filter to manage transmission of broadcast and multicast packets across the switched link to the remote node. However, this filter in the prior art system has to be configured by a network administrator who was knowledgeable about the protocols being used. Thus, most often, the filter was not properly configured, or not configured at all.
Accordingly, it is desirable to provide a remote access server device, which does not need to be manually configured by an administrator, yet effectively manages the transmission of broadcast and multicast packets across the switched network link to the remote node.